Outlet trough and mandrel bar arrangement for tube-piercing mills



ING MILLS G. J. KIRCHNER Sept. 4, 1945.

OUTLET TROUGH AND MANDREL BAR ARRANGEMENT FOR TUBE PIERC Filed Dec. 18, 1943 5 Sheets-Sheet l T Q W INVENTOR [J/ORCHAW,

mm QM R. RN Sm Sept. 4, 1945.

G, J. KIRCHNER 2,384,312 OUTLET TROUGH AND MANDREL BAR ARRANGEMENT FOR TUBE PIERCING MILLS Filed Dec. 18, 1945 5 Sheets-Sheet 4 N m I R Q *3 "3 2 a m ILL- J. 1 5 H L I 3 H} I v I "Ill .1" 1: Q I SI 5: E W

I 1111 I 3 I Q 3 O) H N PM Q n IVENTOR n Add) Patented Sept. 4, 1945 OUTLET 'rnoUG-n AND MA pnEL BAR AB- M Y RANGEMENT FonrUen-rIE-Romo George J. Kirchner, Mount Lebanon, Pa,- assign- I 1 or to National Tube Company, a corporation of New Jersey Application December 18, 19 13, Serial No. 514,846 4 Claims. (o1. .8013) This invention relates to a piercing mill for manufacturing seamless tubes and the like, and particularly, to an improved outlet trough and mandrel bar therefor. i

In the manufacture of seamless tubes by the Mannesmann or Steifel process, a helical motion is imparted to the billet or workpiece by the rolls of the mill rotating it on its axis and atthe same time advancing it over a mandrel arranged in a horizontally dis-posed outlet trough on the delivery side of the rolls. The forward end of the mandrel carries a piercing point or plug while'the rear end is attached to a thrust spindle which permits the mandrel to rotate in the trough with the advancing'billet or workpiece. I

The purpose of the outlet trough is to receive the pierced billet as it emerges from the piercing mill, to support the billet and mandrel bar in longitudinal alignment during rotary emission of the billet from the mill, to provide suitable man drel bar thrust resistance and permit rotation by means of a mandrel bar thrust bearing, andito provide means for withdrawing the mandrel bar from the pierced'billet'at conclusion of the piercing operation and return the mandrel bar to piercing position ior the succeeding billet.

Conventional or existing outlet troughs are designed so as to provide for the production of ordi nary tubular sections of relatively light walLeomparatively large inside diameters and commercially practical lengths varyingfrom 25 to 50. feet. Such arrangements constitute a mandrel bar of sufficient diameter and of sufficient strength in column to resist any buckling action resulting from the thrust of billet inthe piercing operation. In most designs one or possibly two mandrel bar steadiels are applied to reduce effective column lengths of said mandrel bar, and thereby permit the use of lighter mandrels without buckling or undue whipping.

It is evident that the piercing of extremely small inside diameter, heavy wall tubes with such equipment would be a physical-impossibility in View of the small diameter mandrel. required and subsequent lack of mandrel bar steadying or anti-buckling equipment provided in the existing equipment.

Accordingly, it is the general objectof the present invention to provide an outlet trough for accommodating a relatively small diameter mandrel bar whereby the same is rigidly and: securely supported guided so as toprevent buckling or excessive whipping of the mandrel bar so that small diameter seamless tubes and pipe.- can be conveniently manufactured.

It is another object of the invention to provide an improved outlet trough for tubepiercing mills which. can be easily and conveniently inoorpqrated and used with existing equipment- Ill JIt is more specific object oithe inverition to provide an auxiliary outlet trough for tube pierc ing mills having means carried thereby for supporting the mandrel bar at spaced points Sllbf' stantially throughout the length thereof which in one position supports and guides the mandrel bar and in another position assumes a retracted position away therefrom so as topperliiit the billet or workpiece to pass freely'over the mandrel bar to pierce the same with the supporting means being responsive to the movement, of the billet into and throughthe trough.

' It is a further object of the present inveiitionto provide a relatively small diameter mandrel bar complete: with an" improved thrust bearing, are rangement which can be conveniently attached to a larger or conventional mandrelbar Iarid conveniently used withtlie improved trough of my invention.

Variousother ob ectsland advantages of this invention will bemore apparent in the course of the following specification, and will be particularly pointedout in theapp'ended claims.

In the accompanying drawings there is shown, for the-purpose of illustration, an embodiment which myinv en'tion may assumein practice.

Inthesedrawings: L Figure 1 is aplan view oftlie improved outlet trough of my invention:

' Figure 2 is a sectional view taken on line I I -Il ofFigureil i v Figure 3 is a sectional view taken on line IlI'i-II'fbf Fig'ure 1';

Figure 4 1s a sectional view taken ozi line IV-IV'bfFiguie l; p Figure 5- is a sectional view taken on line V.V ofFi'gure l; I

Figure 6 is an enlarged plan viewof the rear of thrust block end of improved outlettrougjh with the ttpjremoveq showing the mandrel ba disposed therein together with the supporting members in their protracted position for sup: poi'tingthesanie; H Figure 7 is" a sectional yie'w taken on line VII'VI-I of Figured; v

:Fig'ure' 8 is a "plus view similar to Figure 6 showing the mandrel bar and the billet being piercedin' position therein; g

Figure 9' is a side View of Figure 8; and Figures 10 and 10'? are longitudinal sectional views thr'oi'igh the improved mandrel bar thrust bearing arrangement of my invention is adapted to beuse'd with my improved outlet trough wherein the 1mesx-X represent the line of juncture oi't'he two figures. I The presentinvention comprises an auxiliary outlet. trough, complete with auxiliary mandrel bar thrust block, mandrel bar steadier, pierced billet kick'out, and billet strip-ping equipment for suecesstully piercing tubes of extremely small inside diameters and heavy walls with the trough, thrust block, bar steadying and kickout equipment being adaptable to outlet trough facilities of existing or conventional piercing mills and utilizing the mandrel withdrawing and returning facilities of such existing or conventional piercing mill outlet troughs. 1 r

Referring more particularly to Figures 1 through 9 of the drawings, the improved outlet trough of my invention comprises a longitudinally extending body member 2 having a bottom wall 3, side walls 4 and a removable top wall 5 so as to provide an open ended box-like structure. As more clearly shown in Figures 2 and 3 of the drawings, the body member is supported preferably on a plurality of spaced apart adapters or brackets 6 which are adapted to fit on and be secured to the base sections 1 of a conventional type of outlet trough of existing piercing mills. There are arranged within the body member 2 on the inner sides of the bottom, top and side walls thereof, removable shims or filler members 8 of the proper thickness to provide proper clearance for the outside diameter of the billet B to be pierced as it passes therethrough and which are adapted to guide andsupport the same in a manner hereinafterto be described. The shims may be attached to the walls of the body member by means of cap screws or any other suitable attaching means so that the shims can be conveniently moved therefrom in case it is desired to replace the same with smaller or larger size shims for piercing different size billets.

There is carried by the removable top 5 and extending to one side thereof, a plurality of outwardly extending arm-like members 9, two in the present instance, which are pivotally attached intermediate the length thereof by means of pins l2 to bosses 10 arranged on the outer side wall of the body member 2, as shown in Figures 1, 3 and 4. There is attached to the extreme outer end of each of the arms 9, preferably a vertically disposed pneumatic cylinder l3, the piston l4 of which is attached to the outer end of the arm by means of a pin IS. The pneumatic cylinder is attached preferably to the base 1 of the existing trough by means of a suitable bracket l6.

At spaced apart intervals. throughout the length of the body member 2, there are arranged in the side walls 4 thereof, pairs of rectangularshaped openings 11 with the openin of each pair positioned directly opposite the other. As more clearly shown in Figure 4 of the drawings, there is arranged in eachof the rectangular-shaped openings l1, a mandrel bar steadying or supporting finger-like member 18 which is slightly smaller in size than the rectangular-shaped opening so as to provide sufficient clearance therearound. There is arranged in the outer end of each of the members 18, preferably a rectangular-shaped open slot l9 in which there is disposed a removable insert member 20 which is held therein preferably by a pair of cap screws 2|. In the outer sides of each of the insert members centrally thereof, there is arranged a semi-circular groove 22 which conforms substantially to part of a diameter of the mandrel bar which is adapted to be used with the trough. In other words, the groove 22 is of such concavity for close guidance of the mandrel bar and insert members 20 are quickly and conveniently replaced for any chirsige of bar size of renewal of worn-out inser Each of the members I8 is preferably attached respective opening l1, preferably by means of a vertically disposed shaft 23 which extends down through the side wall 4 of the body member. The upper end of each of the shafts23 is cylindrical in shape and journaled in a suitable bearing portion 24 arranged in the upper portion of the side wall. The part of each of the shafts 23 that passes through the members 18 is preferably square or otherwise suitably designed so as to be attached thereto whereby the members I 8 rotate when the shafts are rotated. The lower end of each of the shafts 23 is, preferably cylindrical and journaled in a suitable bearing portion 25 arranged in the lower portion of the side wall. The thickness of the members I8 and portions of the shafts 23 are such that when arcuate movement toward the center line of the trough has brought the members 18 at right angles to the center line, as shown in Figure 5, the inner face of the members will bear against the adjacent slot end, thus restricting any further movement in that direction.

Each of the shafts 23 is of sufficient length so as to extend below the bottom of the body member 2, and these extending portions 26 preferably are square and there is attached to each of them, an outwardly extending lug-like member 21 having a slotted opening 28 arranged in the outer end thereof so as to provide substantially a yoke-like portion on the end of each of these members. The members 21 are attached to their respective shafts 23 so that they are disposed at substantially 45 degrees to the center line of the trough and to their respective members l8 when the members are positioned in their protracted positions, as shown in Figure 5. There is arranged and extending between the members 21 of each pair, preferably a coiled spring 39 with the ends thereof connected to the members 21 preferably by means of cap screws 40 for a purpose later to be described. On either side of the body member 2, there is arranged substantially parallel thereto, alongitudinally extending rod 29 which is disposed in and extends through the slotted openings 28 of the members 21 disposed on either side of the body member. There is arranged along each of the rods 29 at a spaced distance from each of the members 21, a collar 30 which cooperates therewith in a manner and for a purpose hereinafter to be described. The rods 29 are mounted for slidable movement along the body member preferably in spaced apart bearing portions 3| arranged on the side walls. At the outer or rearward end of the body member 2, as more clearly shown in Figures 6 through 9 of the drawings, there is arranged a crosshead arrangement 32 consisting of a shaft 33 having an upwardly extending arm 34 arranged on each end thereof with the upper ends of the arms 34 suitably connected to the outer ends of the respective rods 29. There is also carried by the shaft 33, intermediate the length thereof, an upwardly extending arm 35 with the upper end thereof pivotally connected to the outer end of a piston 36 of a pneumatic cylinder 31 suitably arranged below the body member centrally thereof. The shaft 33 of the crosshead is suitably journaled in bearing portions 38 arranged on the endmost adapter 6.

There is arranged in the bottom wall 3 of the members 2 at spaced apart intervals, a plurality of openings 4|, two in the present instance, and there is positioned directly opposite each of these openings, a vertically disposed double-acting pneumatic cylinder 42. Each of the pneumatic cylinders 42 consists preferably of a cylindrical housing 43 which is sec ely attached to the bottom of the body member by means of cap screws 44 or by any other suitable means. The piston rod 45 of each of the cylinders is securely attached to the base of the housing 43, as at 4S, with a piston 41 securely attached to the upper end of the piston rod. There is disposed over and around the piston rod between the same and the housing 43, a cylin der 48 which is designed to move vertically through the respective openings ll in the bottom of the body member for the purpose of lifting or lgicking out the pierced billets in a manner to be described.

At the extreme rearward or thrust block end of the body member 2, as shown in Figures 6 and 7 of the drawings, there is arranged preferably in vertical slots, a stripper block 49 which is preferably of a welded shape having an open top slot 50 arranged therein for passage of the mandrel bar therethrou gh. On the inner side of the blocl; 49, there is arranged, preferably a face plate which is preferably angularly arranged or canted from the vertical transverse plane in the direction of the thrust block end of the trough. It is the purpose of the face plate 5! together with the thrust block 49 to strip the pierced billet from the mandrel after the piercing operation.

"There is shown in Figures and 10 oi the drawings, an auxiliary thrust bearing and cone pling" arrangement for attaching a relatively small diametermandrel bar to the end of a larger size or conventional type mandrel bar which smaller size mandrel bar is adapted to be used with the improved outlet trough of the present inventionf "Ihe auxiliary thrust bearing com prises a hou sing or casing 52 having an outer diameter substantially equal to that of the con ventional or larger size mandrel bar 53 to which it is attached preferablyby means of a threaded connection 54!. There is disposed within the housing or casing 5 2, a rotatable spindle 5,5. of varying outside diameter. There is arranged on the spindle 55 intermediate the length thereof, an anti-friction thrust bearing 55 with the race thereof which is adapted to rotate therewith pressed on the spindle so as to provide a tight fit and abutting against a shoulder 51 of the spindle. The stationary or opposed race of this bearing abuts against a shoulder 58 arranged on the inner periphery of the housing 52. Adjacent the outer end of the spindle 55, there is arranged an anti-friction radial bearing 59 with the outer race thereof having a tight fit with the internal bore of the casing 52 with the inner race having a tight fit with the spindle and abutting against a shoulder 6!] carried thereby. Adjacent the innor end of the spindle 55, there is arranged a smaller anti-friction radial bearing 6! which fits tightly over the spindle and abuts against a shoulder 62 carried thereby. The outer race of the bearing 6| fits tightly around the inner periphery of a smaller diameter portion of the casing 52. There is arranged on a small diameter portion of the spindle 55 directly next to the bearing 5!, a spacer 63 so designed to transmit longitudinal force against the inner race of the opposing spindle shoulder 62 The spacer 63 is forced inwardly by means of an adjustable nut 64 arranged on a threaded end portion of the spindle. The spacer 63 and the nut 64 are retained in proper position, preferably by. lock washer 65 and lock nut 65. The outer diameter of the spacer 63 is maintained at proper magnitude to insure properclearance with the end bore of the casing 52 in which annular V,-shaped grooves Or any other suitable means is provided for establishing a seal between rotating and stationary parts. It will be understood, that the internal bore of the casing 52 at the thrust bear- -ing zone, that is, at the bearing 56, is in excess of the outer diameter of this bearing so as to insure perfect spindle alignment with respect to the anti friction radial bearings 59 and BI.

Adjacent the outer end of the spindle 55, there is threaded into the outer end of the casing 52, a collar retaining member or plug 61 which is provided so as to exert pressure against the inner race of the bearing 59 which pressure is transmitted to the spindle 55 and to the spindle shoulder 50 and thence to the spindle shoulder 51 to the thrust bearing 56,which pressure is resisted by the internal shoulder 58 of the casing 52. When the proper pressure has been applied by the retainer 6'! by tightening the same, such pressure or assembly tightness is maintained preferabl by a plug or set screw 68 arranged in the peripheryof the casing 52 and extending into a hole 69 arranged in the periphery of the retainer 51. The internal bore of the retainer nut 61 is provided with sufiicient clearance with the spindle 5.5 and there are provided preferably annular V-grooves or any other suitable means for establishing a seal between the rotating and stationary parts at this end of the casing. By providing such a construction, it will be seen that any lost motion between the bearing elements of the assembly is eliminated and, should the parts wear, it will be seen the retainer nut 61 can be tightened to compensate for such wear so as to again provide a relatively tight assembly,

On the extreme outer end of the spindle 55, theere is arranged a mating portion 10 for flexible juncture with the complementary mating half H arranged on the inner end of the'small diameter mandrel bar 72. The mating portions 70 and H preferably have spherically radiused or concave-convex mating surfaces, as at 13, so as to provide a flexible connection, but it will be understood that any other suitable connection may be provided at this point. There is provided a split coupling M for holding the mating portions 143 and H in engagement with each other, and at the same time to permit limited move ment of the mandrel bar 12 relative to the spindie. 55.. The external profile and diameter of the coupling 14 is such as to offer no interference with conventional mandrel guiding equipment during longitudinal movement of the mandrel in either direction during mandrel withdrawing or advancing operations. In other words, the coupling '34 has a. smooth outer contour and is pref erablyfrusto-conical shaped with the largest diameter thereof being substantiall equal to the outer diameter of the casing 52.

It will be understood that the small diameter mandrel bar 12 is of suificient length to extend completely through the outlet trough so as to position the piercing point or plug 15 arranged on the outer end thereofat proper piercing position in the piercing mill. The spindleis preferably axially bored as at 1'6, and there is arranged therein and extending therethrough a longitudinally extending small diameter water cooling pipe 'fi' which extends into and through the mandrel bar 12- and terminates adjacent the outer end of the piercing point or plug 75.. The water cooling pipe I? is of such diameter as to provide sufficient clearance between the outer sides thereof and the inner bore of the spindle of the conventional or larger size water cooling pipe I8 arranged in the mandrel 53 by means of a reducing coupling I9.

The improved trough of my invention, together with the auxiliary thrust bar bearing assembly functions in the following manner. It will be understood that the auxiliary trough of the present invention is first assembled in position on the base of or in a conventional or larger size trough by means of the adapters 6 and that the small diameter mandrel bar I2 is attached to the end of the conventional or larger type mandrel bar 53 .by means of the thrust bearing assembly hereinbefore described.

It will be assumed that the fingers or mandrel bar supporting members I8 of the trough are disposed in their respective openings I I in the side walls of the body member, and in position substantially parallel to the center line of the trough, as shown in Figures 1 and 2 of the drawings, with the auxiliary mandrel bar I2 positioned at the outer end thereof ready to be brought forward toward the mill for the piercing operation. A suitable fluid is then introduced into the pneumatic cylinder 31 by any suitable connection and means, and the piston thereof is moved thereby toward the outer or thrust block end of the trough which, in turn, moves the two rods 29 disposed on either side of the trough in the same direction or longitudinally through the action of the crosshead arrangement 32 which is arcuately rotated by means of the pneumatic cylinder. As the rods 29 move, it will be seen that the collars 30 carried thereby also move and abut against the luglike members 21 arranged on the shafts 23, thereby imparting a turning movement thereto. Upon suchturning movement of the shafts 23, it will be seen that the members I8 attached or keyed thereto are moved outwardly to their protracted positions within the trough so as to extend thereinto, as shown in Figures 6 and '7 of the drawings. It will be understood that after the arcuate movement of the fingers or members I8 has exceeded 45 degrees, the tension springs 39 effect completion of a total movement of 90 degrees. As hereinbefore explained, the members l8 are arranged in the slots I! so that when they are moved to their right-angular position or protracted positions, the sides of each of the members I8 abut against the adjacent vertical end walls of their respective openings I! so as to limit the inward movement of these members. In other words, the springs 39 complete the movement of the members I8 so as to position and maintain the same against the vertical end walls of the openings I I which act as stops for such movement of these members. A suitable fluid is then introduced into the opposite end of the cylinder 31 so that it is actuated in the reverse direction whereby the rods 29 together with the collars 30 carried thereby are moved to their original positions with the collars 30 in such position adapted to act as stops for the members 2! upon movement of the supporting members I8 to their original position or retracted position in the side walls, in a manner hereinafter to be described.

The outlet trough is now in readiness to receive the mandrel bar I2 for the piercing operation. The auxiliary or smaller diameter mandrel bar 12 is then moved forward into and through the trough by means of conventional equipment which usually consists of a sheave cable arrangement which operates a conventional thrust carriage in a manner well known to those skilled in the art. As the mandrel bar 12 passes into the trough, it passes into and through the cylindrical openings formed by the semi-circular grooves 22 arranged in the opposed ends of the insert members 20 carried by each pair of fingers or supporting members I8. The outer or mandrel entry side of each of the semi-circular grooves 22 of the insert members is preferably beveled or flared as at 80 so as to aid in guiding and directing the mandrel bar therethrough.

After the mandrel bar has passed entirely into the trough and is disposed therein, it will be understood that the piercing point or plug 15 is properly positioned in the piercing mill for piercing a billet in the conventional manner. It will be seen that the supporting members I8, together with the inserts 20, carried thereby, support the mandrel bar I2 at spaced apart points throughout the length thereof, The thrust carriage is then locked by the conventional mechanism so as to preclude any movement of the mandrel bar as a result of the thrust to which it is subjected during the piercing operation. A cylindrical billet B is then introduced into the piercing mill and passes therefrom over the piercing point 15 and the mandrel I2 into and through the trough. As the billet advances, it is helically rotated with consequent mandrel and auxiliary mandrel bar rotation in combination with longitudinal thrust which is resisted by the thrust bearing assembly and the latching mechanism. As the billet passes over the mandrel bar, it will be seen that the insert members 20, together with the members I8 to which they are attached, reduce the effective column length of the mandrel bar thereby steadying the same and thus precludin any buckling action due to the aforementioned thrust.

As the pierced billet passes through the outlet trough, each pair of fingers I8 together with the inserts 20 carried thereby are successively forcibly displaced as the leading end of the billet comes into contact therewith, as shown in Figures 8 and 9 of the drawings, thereby moving the same about their pivotal connections at the shafts 23 and rotating the same. When the arcuate magnitude of the displacement of the members I8 exceeds 45 degrees, the tension springs 39 will act to effect completion of a degree movement thereof so as to complete the movement of the members I8 and return the same to their retracted positions within their respective openings I! in the side walls of the body member. When the members I8 have been returned to their fully retracted positions within their respective openings I! and are disposed substantially parallel to the mandrel bar or the center line of the trough, it will be understood that the outer ends of the lug-like members 21 will abut against their respectiv collar 30 on the rods 29 which act as stops so as to prevent further outward movement of the members I8. As the billet passes through the trough and over the mandrel bar therein, it will be seen that the shims 8 arranged on the inner walls of the trough act to guide and support the billet a it passes therethrough.

After the billet has (been completely pierced and has moved into the trough substantially the full length thereof, and all of the supporting members I8 have been moved to their retracted positions, the piercing operation is completed and the billet is ready to be removed from its position in the trough. The mandrel latching mechanism is then released and the sheave-cable arrangement is actuated in a direction opposite that for positioning the mandrel bar in the trough and the piercing mill thereby moving the thrust bearing mandrel bar assembly away from the mill and consequently the mandrel out of the trough. As the mandrel moves from the trough, the leading end of the pierced billet B strikes the canted face of the face plate of the stripper block 49, thereby permitting the mandrel bar to be withdrawn therefrom. It will be seen that the canted face of the plate 5| precludes sulbsequent adhesion of the hot pierced billet to the stripper block.

After the mandrel has been removed from the trough, the top 5 is removedby actuating of the pneumatic cylinders l3 so as to permit removal of the pierced billet from within the trough. The pneumatic kick-out cylinders 42 are then actuated so as to lift and move the pierced billet upwardly from the trough through the top thereof to a position thereabove. The billet is then pushed oil the upper ends of the pistons of the pneumatic cylinders 42 preferably onto a skid arrangement S arranged along one side of the trough, as shown in Figure 3, over which they roll and pass to the next operation.

As a result of my invention, it will be seen that there is provided an auxiliary outlet trough and small diameter mandrel bar together with a thrust bearing arrangement, which can be used and conveniently incorporated with conventional piercing mill equipment.

It will be seen also that the improved outlet trough of the present invention rigidly supports the mandrel bar during the piercing operation, thereby eliminating any excessive vibration or buckling thereof, and, at the same time, does not interfere with conventional piercing operations.

While I have shown and described one specific embodiment of my invention, it will be understood that this embodiment is merely for the purpose of illustration and description and that various other forms may be devised within the scope of my invention, as defined in the appended claims.

I claim:

1. Apparatus of the class described including, in combination, an auxiliary outlet trough for a tube piercing mill, means for attaching said trough to conventional piercing mill equipment, a relatively small diameter auxiliary mandrel bar which is adapted to be used with said trough, means carried by said trough for supporting and guiding the mandrel bar when disposed therein, and means for attaching said small diameter mandrel bar to the end of a larger size mandrel bar of the mill.

2. Apparatus of the class described, as defined in claim 1, where the means for attaching the small diameter mandrel bar to the large mandrel bar consists of a thrust bearing and coupling arrangement.

3. In an outlet trough for a tube piercing mill of the class descrilbed including a mandrel bar for supporting a piercer point for piercing billets, a

plurality of spaced apart pairs of members carried by said trough and in one position adapted to extend thereinto for supporting and guiding the mandrel bar when disposed therein at spaced points substantially throughout the length thereof with each member of each of said pairs positioned horizontally on opposed sides of the mandrel bar, means pivotally mounting each of said supporting and guiding members at either side of said trough, arms connected to said pivotally mounted supporting and guiding members which extend outwardly and diagonally therefrom and rearwardly of said trough when said guiding members extend inwardly of said trough in their protracted position and forwardly when said members are in their retracted position, a spring member connecting each pair of oppositely disposed arms for yieldably maintaining each of said supporting members in a protracted position when they extend into said trough for support ing said mandrel bar and for maintaining said members in a retracted position and out of contact with a billet when moved to a retracted pdsition thereby, each pair of mandrel supporting and guiding members adapted to be moved successively out bf a protracted position to a retracted position by the billet as it advances therethrough and to be simultaneously returned to a protracted position by means engaging said arms.

4. An outlet trough for tube piercing mills of the class described comprising a longitudinally extending body member having a removable top Wall and side and bottom walls so as to provide an open ended box-like structure, guide shoes arranged on the inner side of said top and side and bottom walls for guiding the outer sides of the billet as it passes therethrough, a plurality of spaced apart pairs of mandrel supporting members carried by said body member with each member of each pair positioned directly opposite each other and pivotally mounted in the side walls of said body member, said members adapted to extend into the trough in one position substantially perpendicular to said side walls for supporting andguiding the piercing mandrel bar when disposed therein and in another position adapted to assume a retracted position in said side Walls away .from the mandrel bar, and means for moving said supporting members to their protracted positions, each pair of said supporting and guiding members adapted to be moved successively out of engagement with the mandrel bar to their retracted position in the side walls of said body member by the billet upon movement of the same into and through said trough so as to permit the billet to pass freely over the mandrel bar to pierce the same whereby the mandrel bar is supported by said pairs of pivotally mounted members when in their protracted position and the telescoped billet is supported by said guide shoes after said billet has moved said pivotally mounted members to their retracted position.

GEORGE J. KIRCHNER. 

